This invention relates to optical filters and more particularly to imaging with a transverse electrode (or, as sometimes referred to, a "transverse field") electro-optic tunable filter (hereinafter referred to as TEOTF) assembly.
A TEOTF is a device for electronically controlling the transmission characteristics (e.g., wavelength, linewidth, peak transmission, etc.) of an optical filter by the application of voltages to certain birefringent crystals. One filter of such a type is the longitudinal electro-optic tunable filter (hereinafter referred to as LEOTF) which utilizes transparent electrodes to apply voltages to the filter. Since the electrodes are transparent, the light is unaffected by their presence, so that one can easily image through a LEOTF. However, transparent electrodes are not easily attainable. To avoid their need, another type of electro-optic tunable filter was devised, and it is known as the transverse electrode (or field) electro-optic tunable filter (i.e., the TEOTF previously referred to). Although a TEOTF has the obviously great advantage of not requiring transparent electrodes, the TEOTF has the obviously equally great disadvantage that the electrodes obscure the aperture and thereby "destroy" (i.e., significantly and adversely effect) the quality of the image transmitted by the TEOTF.
Although an apparatus and/or method of using the TEOTF with an imaging system without destroying the quality of the image transmitted by the TEOTF is highly desirable, no such prior art apparatus and/or method is known.
It would be fair and accurate to say that apparently the art has accepted the belief that the use of the TEOTF inherently involves its obscured aperture and resulting very poor quality image.